Criminal victimization among adults represents a major public health problem in the U.S. that results in significant negative outcomes and extraordinary long-term costs. Data indicate that as many as one-third of adults have been the victim of at least one violent crime (rape/sexual assault, physical assault, or armed robbery) during their lifetime, and individuals exposed to violence are at risk for developing chronic, debilitating, mental health problems, including posttraumatic stress disorder, depression, and substance abuse. The high prevalence of psychopathology among victims of crime underscores the need for evidence-based interventions that can be readily disseminated for community-based service providers to implement after trauma exposure. Considerable progress has been made in the development and validation of formal treatment programs for chronic mental health problems among crime victims. In contrast, and pertinent to the proposed study, effective interventions have not been validated for addressing the acute unmet mental health needs of this population. Acute interventions are implemented in short temporal proximity to the event with the ultimate aim of reducing risk for longer- term trauma-related difficulties. Despite the limited research on acute interventions for crime victims, researchers recently developed an acute intervention called Psychological First Aid (PFA) for individuals exposed to natural disasters or other catastrophic events. Although promising and advocated by experts, PFA has not yet been evaluated, due likely to the many barriers to conducting treatment research with disaster populations. Importantly, the components of PFA are also directly applicable to victims of violent crime. Further, crime victims are a much more readily accessible population relative to victims of disaster, and an examination of PFA with victims of crime provides a unique opportunity to evaluate this promising but currently untested acute intervention. Thus, the purpose of this R34 project is to implement and refine research protocols that would be required for a full-scale randomized controlled trial of PFA for crime victims. Specifically, this project wll implement and examine the feasibility of a protocol for recruiting, assessing, and retaining acute crime victims in the study (Aim 1). Additional preliminary work that is essential for treatment research will also be completed, including the development and evaluation of a PFA fidelity instrument (Aim 2) and the refinement and testing of protocols for training paraprofessionals to a high level of PFA fidelity (Aim 3). Finally, a controlled pilot study will be conducted to examine the effects of PFA on key mental health outcomes (Aim 4). If the findings from this study are sufficiently promising, the research protocols will be further refined in preparation for a larger randomized controlled trial of PFA with victims of crime.